North Korea test-fired a ballistic missile into the sea off its east coast on Wednesday, South Korea's military said, ahead of a summit between U.S. and Chinese leaders who are set to discuss Pyongyang's increasingly defiant arms program.

The missile flew about 60 km (40 miles) from its launch site at Sinpo, a port city on North Korea's east coast, the South Korean Office of the Joint Chiefs of Staff said in a statement. Sinpo is home to a North Korean submarine base.

The launch comes just a day before the start of a summit between U.S. President Donald Trump and Chinese President Xi Jinping, where talks about adding pressure on the North to drop its arms development will take center stage.

"The launch took place possibly in consideration of the U.S. -China summit, while at the same time it was to check its missile capability," a South Korean official told Reuters about the military's initial assessment of the launch.

The missile was fired at a high angle and reached an altitude of 189 km (117 miles), the official said.